Lieberman, who caucuses with Senate Democrats, expressed his "strong" support for the temporary extension of the across-the-board tax cuts in a speech to the Middlesex Chamber of Commerce in Connecticut. His support for the Republican position of not raising any taxes in the midst of a recession highlights the intense battle set for Congress as lawmakers return to Washington Monday.

"I don't think it makes sense to raise any federal taxes during the uncertain economy we are struggling through," Lieberman said. "In our current economic situation, we cannot risk the economic headwinds that would be caused by tax increases. We need to keep as much money as possible in people's pockets and business's bank accounts."

Lieberman's speech Monday came only a day after House Minority Leader John Boehner (R-Ohio) softened his stance on the tax cuts, which are set to expire Jan. 1, by telling CBS News he would vote in favor of a more tailored extension of the cuts, not including the wealthiest three percent of Americans, if it becomes the "only option" he has.

But the battle over if - and how - to extend the Bush Era tax cuts, given the political climate and the burgeoning deficit, could be even more dramatic in the Senate, where it would only take a few senators, such as Lieberman or Ben Nelson of Nebraska on the Democratic caucus side or conservatives like Jim DeMint of South Carolina on the Republican side, to block action if the tax extensions aren't granted to all Americans.

"I know that many people, including the President, have argued that the tax cuts should not be continued for people making more than $200,000 a year, but to me these are the people we need to be using their income to spend and invest to spur growth and job creation," Lieberman said. "The fact is that the top 3 percent of American income earners account for 25% of the consumption in our economy.

"I want the top income earners in our country to have the confidence and the money to spend and invest over the next year, rather than worrying about paying more in taxes to the federal government," Lieberman said.

A GOP aide said the Lieberman speech shows Democrats are fracturing a bit on the issue.

"Going the next step, and sending out a press release, to promote your position, that shows you a lot about where the politics are on this issue," a GOP aide said.